Magnetic drilling-jig.



UNITED vSTATES 'PATENT 'Ormea- ADOLPH DE'LEEUW, O F HAMILTON, OHIO.

MAGNETIC DRlLLlNG-JIG.

SPECIFICATION forming part of Letters Patent No. 710,257, dated september 30, 1902.

' Application sled March 24,1902. semi No. 99,638. (no model.)

` To all whom' il; nir/,y concern,.-

Be it known that l, AnoLPH L. DE LEEUW, a citizen of the United St:1tcs,residing at Hamilton, Butler county, Ohio, have invented cer- 5 tain new anduseful Improvements in Magnetic Drilling-Jigs, of which Uhr following is a specification.

l This invention relates to a magnetic jig designed for use by machinists in accurately guidingdrills in positions indicated by a properly-located center-punch mark, the jig being magnetically secured to the face of the work and the drill being guided by a' bushing therein.

The `rdinary method for securing the accurate location of adrilled hole may be briefly describedas follows: The center for the hole is marked with a deep center-punch mark to receive the point of the drill, and around ,it is scribed a concentric circle, generally accentuated by means of. light prick punch marks. The drilling is then started, and when the bits of the drill have fairly entered then the drill is removed and the work is inspected to see if the countersink produced by the drill-bits is concentric with the scribed circle.

Drills have a tendency to work over sidewise after `being properly started, and conse quently the initial Work is quite apt to be eccentric. To correct this, a light groove is cut down the proper side of the countersink and the test is repeated until nally the countersnk is found to be concentric with the scribed circle, whereupon, carefully watching for recurring errors due to the side runnin-g of the drill, the drilling may be proceeded with. These corrective measure by grooving the countersink must be brought to full fruition before the drill enters the work the f ull depth of its bits. The method is slow, expensive, and generallyunsatisfactory. In thewuse of my improved jig the jig is properly centralized with reference to the central mark and then secured to the dwork in that position by magnetic attraction, the drilling then proceeding through a bushing known to'be con-V centric with the desired center. l'

The invention will be readily understood from the following description, taken in connection with l the accompanying drawing, which is a vertical diametrical section of a sertedwithin the bushing 3 aud formed, preferably, of hardened material, the bore of this bushing 4 being the size of the hole to be drilled; 5, a center plug litting the bushing 4 and susceptible of movement therein by hand; 6, the energizing-coil surrounding the core l; 7, a metallic jacket surrounding the core and having its upper portion carriedinwardly to join the core l and form a roof over the coil, the lower face of the jacket 7 being even with the lower face of the core 1, the parts l and '7, in conjunction with the coil, forming an iron-clad magnet with lower concentric polar'faces; 8, a retaining-ring disposed in the' magnet structurebelow the coil and formed, preferably, of lead; 9, the dexible conductors leading outward from-the coil, and 10 the terminals of these conductors, adapted for .connection with the conductors from which the supply of current is derived.

In using the device the center of the desired holeis Vrst marked with a center-punch. The jig is then set over the work with the point of the center 5 in the center-punch mark, thus locating the jig'withthe bore of its bushing concentric to the center-punch mark. The

current is then turned on, thus energizing the magnet and fixing the jig firmly to the work. The center 5 is then removed and the drill is fed through the jig, thus insuring that the drill will be guided concentric with the center-punch mark. The jig may, if desired, be continued vin use until the drilling is done, or it may be abandoned after the drill has entered the work beyond the depth of its bits. l

The .bore of the bushing 4 will be such as to suit the size ofdrill to be dealt with, and these bushings will of course be provided in selective sizes. If there is but one of the centers 5 and 'that is of a size to suit but a given bush, then thatrgiven bush will require to be used'n locating the jig. If the hole to be drilled is of a size di'erent from that of the loo bushing suiting the center 5, then after locat- Y -ing and ixing thejig thefbushingemployed in connection with the center will require to be removed and a-bushing substituted of a properv size to suit the drill, or, on the other hand, the particular bushing 4 may be considered or made part of the center 5, so that, practically considered, the center 5 can be used in the bushing 3 without any extra bushing, the large-bodied center being removed after the jig is located and fixed and a propersized bushing for drilling being then inserted in the jig.

In practical construction I nd'it advantageous to make the magnet structure of a single piece of magnetic metal accurately faced off below and centrally bored for. the bushing 3 and concentrically grooved to receive the coil 6, which coil is completed and wrapped, &c., before being inserted in the groove, the lead ring 8 being then fixed in place to hold the coil in the groove. The terminals l0 of the iiexible conductor may advantageously take the form of a double contact-plug, such as usually forms the base of an ordinary incandescent lamp, the conductor of the jig being thus adapted for convenient connection to an ordinary lamp-socket, the energizingcurrent being thus taken from the lightingclrcuit. A

The particular exemplication which has been described is adapted for general Work of the class indicated; but the general principle of the invention will well lend itself to nuy merous modifications of construction, adapting it to special situations.

A The present invention must not for an instant be confused with electromagnetic devices for holding work in Vdrilling-machines or for holding .portable drilling-machines to the Work, for the tendency of nnguided drillpoints is to work erratically, as hasv been explained, quite regardless of whether the workY be held in relation to the journal of the drillspindle by means of electromagnets, clampbolts, or other devices. l

. My invention is applicable to cases where the drilling-machine and work are held in association by electromagnetic means, as well f as in cases where the association is effected by othermeans. i

I claim as'my invention- A 1. In a drilling-jig, 4the combination, substantially asset forth, of an electromagnet having a polar face adapted for contact with the surface of the work to be'drilled and provided with a cylindrical gnideway having itsl axis at right angles-to the plane of said polar face and terminating at or near. the plane of said polar face, anda vconcentric` guiding'l bushing separablydisposed within said guideway and-adapted to engage the' body of the drill near Athe cutting-lips thereof.

2. In a drilling-jig, the combination, sub-4 stantiallyl as set forth, of an electromagnet having a polar face adapted for contact with the surface of the work to be drilled and provided with a cylindrical guideway having its axis at right angles to the plane of said polar face and terminating at Vor near the plane of said polar face and adapted to engage the body of a4 drill, and a conically-pointed center plug concentrically disposedwithin said guideway and mounted for endwise movement therein and removable therefrom.

3. In a drilling-jig, the combination, substantially as set forth, of an electromagnet having a polar face adapted for contact with the surface of the work to be drilledand provided with a cylindrical guideway having its axis at right angles to the plane of said polar face and terminating at or near the plane of saidpolar face, a bushing of non-magnetic material fixed Within said gu-ideway, and a drill-guiding bu shin gseparably disposed within said first-mentioned bushing and adapted to engage the body of the drill.l

4. In a drilling-jig, the combination, substantially as set forth, of an electromagnet having la polar face adapted for contact with the surface of the work to be drilled and pro.- vided with a cylindrical guideway having its axis at right angles to the plane of said polar face and terminating at or near the plane of said polar face, a concentric bushidg separably disposed within said guideway and adaptved to engage the body of the drill, and a con- -ically-pointed center plug separably disposed virithin said bushing.

-5. In a drilling-jig, the combination, substantially as set forth, of an electromagnet having a polar face adapted for contact with the surface of the work to be drilled and provided'with a cylindrical gnideway having its axis at right angles to the plane of said polar face and terminating at or near the plane of said polar face, a bushing Aof non-magnetic material fixed within said guideway, a concentric bushing separably disposed within said first-mentioned bushing and adapted to engage the body of the drill, and a conicallypointed center plug separably disposed Within said separable bushing.

6. In a drillng-jig,.the combination, substantially as set forth, of a disk formed of magnetic material and having its lower face concentrically grooved and having a central bore, an energizing-coil vdisposed Within said groove, anda center plug concentrically and separably disposed within said central bore. 7. In a drilling-jig, the combination, substantially as set forth, of a disk` formed of magnetic material and having its lower face concentrically grooved and having a central bore, an energizing-coil disposed within said y groove, a lining-bushing of non-magnetic material fixed in said central bore, a concentric bushing separably disposed Within said lining-bushing, and a clinically-pointed center plug disposed within said separable bushing. Y 8. In a drilling-jig, the combination, substantially as set4 forth, of a disk formed of magnetic material and having its lower face concentrically grooved and having a central b ore, an energizing-coil disposed within said groove, a retaining-ring of non-magnetic ma- IIO terial secured to said disk and forming a floor to said concentric groove, a concentric bushing separably disposed wit-hin said bore, and a conically-pointed center plug concentrically and separably disposed Within said bore.

9. In a drilling-jig, the combination, substantially as set` forth, of a guide having a cylindrical drill-guiding bore Whose inner end terminates in substantial juxtaposition with the face 0f the work when the jig is in position on the work whereby it is adapted to engage the body of the drill at the surface of the work to be operated upon, and an electromagnet connected therewith and adapted to adjustably fix said guide in relation to the Work to be drilled.

10. Tlreimproved centering and drilling jig comprising a guideway transversely adjustable upon the face of thework to be drilled and adapted to engage the body of the drill to be employed and adapted to alternatively engage a`center plug, an electromagnet connected with said guideway and serving to hold it to the face of the Work after adjustment, and a cylindrically-bodiedconically pointed center plug adapted to fit said guidewayand serve in positioning the guideway concentric with a center-mark engaged by the point of the center plug, combined substantially as and for the purpose set forth.

11. Theimproved centering and drilling jig comprising a jig-body having a guideway whose inner end terminates in substantial juxtaposition withthe face ofthe work when the jigv is in position on the work whereby it is adapted to fit the' body of a drill and h'av- 'ing a contact-surface at right angles -thereto to engage the flat surface of the Work to be drilled, and means for sticking said contactsurface to the flat surface of the work independent of the marginsof the surface of the work, substantially as and for the purpose set forth.

12. The improved device for aiding inthe production of drilled holes concentric with a center-punch mark established in the surface of the Work, said device consisting of a jigbody having a guideway whose inner end terminates in substantial juxtaposition with the face of the Work when the jig is in position on the work whereby it is adapted to engage the body of the drill and be shifted over thc surface of the work till it is concentric with the established center-punch mark, means for sticking said guideway to the surface of the work after it has been adjusted, and a concentric-pointed center plug slidably and removably mounted in the guideway of the jig and serving to position the jig while the point of the center plug is in the established center-punch mark, substantially as and for the purpose set forth.

13. The improved device for aiding in the production of drilled holes concentric with a center-punch mark established with the surface of the Work, said device consisting of a cylindrical plug with a pointed end adapted to be set in said center-punch mark, a jigbody having a guideway in which said lplug slidablyand removably its and havinga contact-surface at right angles to the axis olsaid guideway, and means for sticking said contact-surface to the surface of the work While the guideway engages the body of the plug and the point of the plug engages the established center-punch mark, substantially as .and for the purpose set forth.

ADOLPlI L DE LEEUW. 

